I don’t want to put words in e_t_h’s mouth, but I think the point is that God’s plan called for their sin definitely to happen. God, however, never committed nor condoned the sin at any point. The creatures were free not to sin, but did so anyway.
Ears to hear said in this thread that God is the 1st cause of every event. Therefore, God caused them to sin. Which means they were not free to either sin or not sin.